44-25 Exhibit A-DPW_VI Sampling_1.17.2025.pdf

A Preliminary Assessment was conducted as part of due diligence by Matrix in 2021 which identified additional areas of concern (AOCs) at the Site including the need for additional vapor intrusion evaluation in accordance with the May 2021 Vapor Intrusion Technical Guidance. Therefore, during the heating season in 2023, Consulting & Municipal Engineers Associates (CME), completed an additional vapor intrusion investigation at the Site. The vapor intrusion investigation was performed to evaluate the potential impacts to indoor air quality due to groundwater impacts identified in monitoring well MW-10 at concentrations exceeding the NJDEP Vapor Intrusion Groundwater Screening Levels (VIGSL) and the presence of LNAPL in monitoring well, MW-9. During this sampling event, three IA samples, six SSSG samples, and one AA sample were collected from the Site. Based on the analytical results, benzene and ethylbenzene were identified in the IA samples above the indoor air remediation standards but below the rapid action levels and Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL), the National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV). The benzene and ethylbenzene impacts identified in the IA samples were most likely associated with Site operations as these compounds were not identified in the SSSG samples. However, TCE was identified in the SSSG samples above the soil gas screening levels and the Residential Indoor Air Remediation Standards (RIARS) but below the Non-Residential Indoor Air Remediation Standards (NRIARS) and the OSHA and NIOSH standards identified above. Based on results of previous investigations and as per the NJDEP Vapor Intrusion Technical guidance long-term monitoring for vapor intrusion is recommended. Matrix will coordinate the necessary access to conduct the vapor intrusion activities at the Site. The vapor intrusion investigation activities will include the collection of SSSG, IA, and AA samples from within and beneath the Site building. At least 24 hours prior to completing the SSSG and IA sampling, Matrix will complete a building walkthrough (Site inspection) and removal of any potential background sources. Matrix personnel will complete the NJDEP Indoor Air Building

ng the SSSG and IA sampling, Matrix will complete a building walkthrough (Site inspection) and removal of any potential background sources. Matrix personnel will complete the NJDEP Indoor Air Building Survey and Sampling Form for the Site. Based on the results of the 2023 vapor intrusion sampling activities and in accordance with the NJDEP May 2021 Vapor Intrusion Technical Guidance (Version 5.0), long term monitoring is required for the Site building. The May 2021 Vapor Intrusion Technical Guidance states that long term monitoring is required for a Site without a mitigation system installed as the appropriate mitigation action. The frequency of inspections and sampling events is based on the SSSG concentrations. Therefore, Matrix is recommending the completion of the following sampling plan for the 2025 heating season (Samples should be completed before March 31st). 1. Commercial – 25 Lakeside Avenue, West Orange, New Jersey (approximately 51,815 square feet) a. eight sub slab soil gas samples (three in the office area and five in the garage area), four indoor air samples (three in the office area and only one in the garage area break room), and one ambient air sample. Please note that indoor air samples will not be collected in the garage portion of the Site with the exception of the break room as operations in the garage area use, handle, or store the same investigative contaminants of concern (COCs) as found in the soils and groundwater. The IA/AA samples will be placed on hold and the SSSG samples will be analyzed for volatile organic compounds (VOCs) via USEPA TO-15 method. The IA/AA samples will be collected prior F:\2025\25-0037 West Orange DPW\Proposal\LTM VI Proposal\DPW_VI Sampling_1.17.2025.docx 2